Synthesis of poly(phenylsilsesquioxane) having organostannyl groups

Poly(phenylsilsesquioxane) (PSQ) having tributylstannyl groups (TBPSQ) was prepared from phenyltrimethoxysilane and bis(tributyltin) oxide [(Bu3Sn)(2) O] under basic conditions. The procedure, using a catalytic amount of basic reagent such as triethylamine, sodium hydroxide, or aqueous ammonia., affo rded yields of TBPSQ based on Si in the range of 12-45% at a number-average molecular weight precipitated from ethanol of about 3500. In the other pro cedure, starting from PSQ with (Bu3Sn)(2)O, the incorporation of tributylst annyl groups into PSQ proceeded effectively in the presence of an acid cata lyst such as methanesulfonic acid or sulfuric acid, giving TBPSQ in moderat e yields of greater than 52%. Dibutyltin oxide, a bifunctional organotin co mpound, was also used, affording dibutylstannylated poly(phenylsilsesquioxa ne) (DBPSQ) without crosslinking. The highest ratio of Si and Sn contained in TBPSQ or DBPSQ, prepared under acidic conditions, was Si/Sn = 7/1. (C) 2 001 John Wiley & Sons, Inc.